Compound and method for conditioning boiler, steam and condensate systems



Patented Sept. 1, 1936 COMPOUND AND METHOD FOR CONDI- TIONING BOILER,STEAM AND CONDEN- SATE SYSTEMS Morris E. Dreyfus, Kansas City, Mo.,assignor to Western Chemical Company, City, Mo., a corporation ofMissouri N Drawing. Application February 18, 1934, Serial N0. 711,553

13 Claims.

This invention relates to a compound and method for treating water,steam and condensate and entrapped gas in boiler, steam and condensatesystems for the arrest, prevention, and inhibition of rust, corrosion,pitting and similar deteriorative effects.

It is well known that such deteriorative effects take place most rapidlyin acid environment and consequently it has been common practice toinject into the boilers, alkaline or basic substances, for example,caustic soda to maintain an alkaline condition therein. Such substancesremaining within the water do not accompany the steam distilled and donot condense with, nor do they I that many points at which thecondensate begins to occur are inacessible for treatment and, besides,such treatment must be continuous for the reason that the treatedcondensate is continually being replaced by fresh condensate.

It is, therefore, a principal object of the present invention tomaintain all of the parts of such systems under the protection of analkaline environment.

In accomplishing this object, I provide a water treating compound whichmay be dissolved in the boiler water, volatilize with the steam,condense with the condensate, to form a solution therewith for return tothe boiler, so that all parts oi the system are retained in theprotecting envirofnment of the compound in one or the other of its andso that the compound does not tend to collect or remain in any one ofits phases.

'I'he acid or corrosive agent usually found in steam; systems iscarbonic acid formed by the combination, of carbon dioxide and water,the carbon dioxide having found its way into the system as a constituentof the air admitted, as a product in solution in the boiler feed water,as a product of decomposition of acid carbonates or bicarbonates, or asa product of decomposition of the normal or basic carbonates in theboiler water.

It is, therefore, another object of the invention to provide a compoundcapable of neutralizing or absorbing any carbon dioxide, carbonic acidor other acid corrosive agent which may be present.

In carrying out my invention, I have found substances which are capableof neutralizing or absorbing the carbon dioxide, carbonic acid or otheracid corrosive agent and at the same time are also capable of followingthe respective phases of the boiler feed water so that all parts of thesystem including the condensate portions are subjected to treatment.

I have found that best practical results are attained through use ofwater soluble, alkaline and volatile nitrogenous substances having aboiling point at atmospheric pressure no higher than 171 C. and no lowerthan 0 C. Substances with normal boiling points higher than this rangehave a vapor pressure so low that their volatility with steam is reducedto a point where satisfactory results are not attained. Substances withboiling points lower than this range have a vapor pressure so high thatthey will not condense with the steam to dissolve readily in thecondensate. My invention, therefore, contemplates substances havingboiling points at atmospheric pressure from 0 C. to 171 C.

Substances which meet these requirements are from the following chemicaltypes including: substituted ammonia compounds; amines and aminocompounds; primary amines, in which one hydrogen atom of the ammoniamolecule has been replaced by a chemical group; secondary amines, inwhich two hydrogen atoms of the ammonium molecule have been replaced bychemical groups; tertiary amines, in which the three hydrogen atoms ofammonia have been replaced by chemical groups; and quaternary ammoniumbases in which four hydrogen atoms attached to the nitrogen of ammoniumhydroxide have been replaced by chemical groups.

Since aromatic compounds of the character noted have boiling pointsabove the specified operative range, it is to be understood that thepresent invention contemplates only non-aromatic substances, namelyaliphatic and heterocyclic compounds having water soluble, alkaline andvolatile characteristics.

Any one of the water-soluble alkaline and volatile substances from theabove classes having a boiling point as above specified is introducedinto the system for treating the boiler water, steam, and condensate; orthe substances may be introduced into the boiler feed water prior toadmisleasing the chemical compound in its sion to the boiler. Uponintroduction into the system, the substances volatilize with the steam,condense with the condensate, form a solution with the condensate andremain continually in 5 intimate contactwith all of these phases,thereby maintaining a'n'alkaline, caustic, or basic condition in all ofthe several phases, neutralizing and absorbing carbon dioxide, carbonicacid and all other acids which may be present throughout the entiresystem, to inhibit corrosion, and similar deteriorative efiects. It isthus obvious that while the substances need be introduced at only onepoint in the system, their volatile and watersoluble characteristicsmake them available for treating all parts of the system.

alkaline and volatile properties of the compound after its cycle throughthe vapor and condensate parts of the systems. In these types ofsystems, it is desirable to maintain a strong alkaline condition in theboiler water, for example, by the addition to the water ofa strongerbase than the chemical to be employed, such'as caustic soda, whichsubstance does not volatilize, but remains in solution in the boilerwater.

The chemical compound upon admission to the boiler volatilizes andpasses ofi into the steaming space of the boiler with the steam and intoall parts of the system. The compound is carried with the steam to thecondensate part of the system to intimatelyi'contact all metal parts,for

40 maintaining an alkaline condition which effectively inhibits theformation of rust, corrosion and similar deteriorative effects, thevapors condensing with the steam and forming a solution in the.condensate absorb or neutralize carbonic acid and any acidity that maybe present in the condensate part of the system. The compound thenreturns to the bofler in the form of a salt of the acid absorbedtogether with any excess of uncombined chemical. Upon contacting thestronger base in the boiler, the salt will react with the stronger baseto again free the volatile base element in its alkaline and uncombinedform to continue the cycle. The rate at which the compound is convertedin the respective phases is substantially uniform so that the compounddoes not excessively collect in any one part of the system. I

In selecting the specific chemical from any one of the types asabove-enumerated, it should be noted that the boiling point of thatcompound at the pressure in the system may be considerably higher thanthe temperature in' the boiler without interfering with its. use. -Thisis due to the 'well known principle ofdistillation with steam i i' whichdependsgjnpon lfijejvapor pressure of the chemical compound at" hetemperature of the flsteaini' Forexampleftliejprimary amine, monoethanolamine, has-a'boiling point of 171 0. at atmospheric'pressure, but at thetemperature of 0 100 0., prevailing in steam boilers at atmosphericpressure, the vapor pressure of the monoethanol amineillows it toevaporate steadily and continuously into the'changing atmosphere of thecurrent of-steam. 1 U- Among the specific substances (together withtheir boiling points at atmospheric pressure) which I have found bestsuited to my process are mono-amyl-amine, 102 0.; di-ethylenediamine,146 0.; di-ethyl-amine, 55 0.; monoethylene-diamine, 117 0.;iso-amyl-amine, 95 0.; di-propyl-amine, 110 0.; pyridine, 116 0.;propylamine, 49 0.; iso-propylamine, 33 0.; and the above mentionedmono-ethanol-amino, 171 0.

While I have specifically described introduction of the volatilechemical into the boiler, it is obvious that it may be introduced intoany part of the system. It is also obvious that the chemical 'may beused in any type steam plants whether used for heating, power, orindustrial processes and that all parts of such systems are subjected totreatment including the boiler or heaters, evaporators, radiators,tanks, piping, pumps, engines or turbines, condensers, valves, traps, orother equipment that may be connected into the system.

What I claim and desire to secure by Letters.

no higher than 171 C. at atmospheric pressure and no lower than 0 C. atatmospheric pressure and capable of volatilizing with the steam andcondensing with the steam and dissolving in' the condensed steam.

2. The process including introducing into a I steam system an alkaline,water-soluble, volatile, aliphatic amine having a boiling point nohigher than 171 C. at atmospheric pressure and no lower than 0 C. atatmospheric pressure and capable of volatilizing with the steam andcondensing with the steam and dissolving in the condensed steam.

3. The process including introducing into a steam system an alkaline,water-soluble, volatile, heterocyclic amine having a boiling. .point nohigher than 171 0. at atmospheric pressure and no lower 0 at atmosphericpressure and capable of volatilizing with the steam and condensing withthe steam and dissolving in the condensed steam.

4. The process including introducing into a steam system an alkaline,water-soluble, volatile, aliphatic amine having a boiling point nohigher than 150 0. at atmospheric presfsnre and no lower than 30 0. atatmospheric pressure and capable of volatilizing with the steam andcondensing with the steam and dissolving in the condensed steam.

5. The process including introducing into a steam system an alkaline,water-soluble, volatile, non-aromatic amine having a boiling point nohigher than 125 0. at atmospheric pressure and no lower than 45 0. atatmospheric pressure and capable of volatilizing with the steam andcondensing with the steam and dissolving in the condensed steam.

6. The process including introducing into a "festeam system an alkaline?water-soli-ible, 'volatile,

gheterocyclic amine having a boiling point no) higher than 120 0. atatmospheric pressure and no lower than. 75 at atmospheric pressure and'capable of volatilizing with the steam and condensing with the steamand dissolving in the condensed-steam.

7. The -process including introducing into a steam system-; an alkaline,water-soluble, volatile, alipha'tic'amine having a boiling point nohigher than 115 C. at atmospheric pressure and no lower than 85 C. atatmospheric pressure and capable of 'volatilizing with the steam andcondensing with the steam and dissolving in the condensed steam.

8. The method of conditioning steam system of the character described toprevent corrosion of the metal parts of the system including maintaininga strong base substance in solution in a part of the system, circulatingthrough the system an alkaline, water-soluble, volatile, non-aromaticamine having a boiling point no higher than 171 C. at atmosphericpressure and no lower than C. at atmospheric pressure, formaintaining analkaline condition in other parts oi the system, and returning saidamine through the strong base solution for converting said amine toits'uncombined state for recirculation through the system.

9. The method of conditioning steam systems of the character describedto prevent corrosion of the metal parts oi the system in contact withthe condensate, including maintaining a strong base substance insolution in the evaporating zone of the system, circulating through thesystem an alkaline, water-soluble, volatile, aliphatic amine having aboiling point no higher than 171 C. -at atmospheric pressure and nolower than 0 C. at atmospheric pressure, tor maintaining an alkalinecondition in the condensate part of the system, and returning said aminethrough the strong base solution for converting said amine to itsuncombined statejor recirculation through the system.

10. The method of conditioning steam systems of the character describedto prevent deteriorative eilects of acidity on metal parts of the systemin contact with the condensate, including maintaining a strong basesolution in the water of the 5 evaporating zone of the system,introducing into said solution an alkaline, water-soluble, volatile,aliphatic amine having a boiling point no higher than 171 C. atatmospheric pressure and no lower than 0 C. at atmospheric pressurewhereby said amine volatilizes with formation of the steam, circulatingthe volatilised amine with the steam forming a solution of said aminewith the condensate, returning the condensate solution to theevaporating zone wherein acid picked up by said amine combines to form asalt of the acid with the strong base andsaid amine, is converted touncombined form ior repeating the cycle of circulation.

11. The process including introduction of a monoethanol amine into asteam system for maintaining an alkaline condition in all parts of thesystem to neutralize acidity in the system.

12. The process including introduction of amylamine into a steam systemfor maintaining an alkaline condition in all parts of the system toneutralize acidity in the system.

13. Theprocess including introduction of dig propyl-amine into a steamsystem for maintainan alkaline condition in all parts of the system toneutralize acidity in the system.

MORRIS E. DREYF'US.

